Tool holders are known which include long cylindrical or tapered shanks which insert into an axial bore of a tool support member. The tool holder is typically secured by means of a set screw which screws into engagement with the tool shank. The set screw sometimes includes a bevelled or faceted end which engages with an inclined surface on the shank of the tool holder so that when the screw is tightened, the tool holder is pulled rearwardly against the support member.
One problem associated with these types of tool holders is that they do not give repetitive and accurate angular location between the support member and tool holder. In the past, tool holders have been located by providing a keyway in either the tool shank or the tool shank bore which cooperates with key element in the other member. Another method which has been tried is to provide one or more flat surfaces on the tool shank which are engaged by the ends of the set screw. In each of the above cases, the accuracy and repeatability of the radial location between the two parts is not as desired.